TerminalFormattedString

Overview

TerminalFormattedString provides a lightweight, readable, and portable way to format and store formatted strings for output on a tty, such as the MacOS Terminal app. It uses ANSI escape sequences for applying text color, background color, and text styles.

Specifying text formatting is straigtforward and familiar to those setting color properties in IDEs such as XCode, and it should read like plain English.

var formattedText = TerminalFormattedString("Hello, World!",
                                            foregroundColor: .red,
                                            backgroundColor: .blue,
                                            style: [.bold, .italic])

ANSI escape sequence data for Select Graphics Rendition (SGR) can be summarized as an integer, which make foregroundColor, backgroundColor, and style, easily expressed through integer enums. Enums also allow XCode and other IDEs to provide a dropdown menu of options for foregroundColor, backgroundColor, and style. style is a Set and can contain multiple options, in order to allow combined text styles such as bold and underlined text.

(The enum implementation comes from ColorizeSwift, which extends the String builtin and is worth checking out.)

Usage Examples

Reusable Indicators

TerminalFormattedString is useful for formatted text that is formatted once and reused. It also can be combined with string literals using the + operator.

var isJavascriptEnabled: Bool = false
var isJSONLibraryInstalled: Bool = true
var isServerConnected: Bool = true

var testPass = TerminalFormattedString("Pass",
                                        foregroundColor: .green,
                                        backgroundColor: .black,
                                        style: [.bold])

var testFail = TerminalFormattedString("Fail",
                                       foregroundColor: .red,
                                       backgroundColor: .black,
                                       style: [.bold])

print("[ " + (isJavascriptEnabled ? testPass : testFail) + " ]" + " JavaScript Enabled")
print("[ " + (isJSONLibraryInstalled ? testPass : testFail) + " ]" + " JSON Library Installed")
print("[ " + (isServerConnected ? testPass : testFail) + " ]" + " Connected to Remote Server")